Engineering Answers

The work break down structure WBS is used to communicate works to be carried out by the contracting stage.

True orFalse

A foot step bearing has a shaft 140 mm diameter is counter bored with a hole of 70 mm diameter al the end. The shaft rotates at 120 rpm. Calculate

(a) The axial load

(b) Frictional Torque

(c) Heat generated al the bearing if the allowable bearing pressure is 0.8 MN/m² by using Uniform wear theory.

Take coefficient of friction, mu = 0.045

A 3 cm diameter tube is used to measure the binary diffusion coefficient of water vapor in air at

20°C at an elevation of 1600 m where the atmospheric pressure is 83.5 kPa. The tube is partially

filled with water, and the distance from the water surface to the open end of the tube is 40 cm.

Dry air is blown over the open end of the tube so that water vapor rising to the top is removed

immediately and the concentration of vapor at the top of the tube is zero. In 15 days of

continuous operation at constant pressure and temperature, the amount of water that has

evaporated is measured to be 1.23 g. Determine the diffusion coefficient of water vapor in air at

20°C and 83.5 kPa. Given, the pressure of water at 20°C is 2.34 kPa.

A lab technician, working in a lab has poured liquid chloroform into a test tubes with inner 

diameter of 25 mm. The test tube holds an amount of 29.46 cm3

liquid chloroform at a level of

1 cm from the top (Figure 2). The chloroform molecular weight and vapor pressure is 119.38 

kg/kmol and 21 kPa respectively. The evaporation of chloroform to the surrounding air is 

occurring at 25 C and 1 atm. If the diffusion coefficient of chloroform in air is DAB is 0.104 cm2

/s, 

determine the rate of evaporation and the time taken for half of the chloroform to be evaporated

at the stated condition. Given the density of the chloroform is 1.49 g/cm³.

An 8 cm internal diameter with 30 cm high pitcher half filled with water is left in a dry room at 

15°C and 87 kPa with its top open. If the water is maintained at 15°C at all times, determine how 

long it will take for the water to evaporate completely. Given, the saturation pressure of water 

at 15°C is 1.705 kPa

a horizontal tube carrying hot water has a surface temperature of 355.4 K and the outside diameter of 25.4 mm. The tube is exposed to room air at 294.3 K. Calculate the nature convection heat loss for a 1 m length of pipe. if the tube is replaced with two horizontal plate and the bottom plate is hotter than the upper plate. compared the resulted value of natural convection heat loss using tube and plate

a glass window with an area of 0.557 m² is installed in the wooden outside wall of a room. The wall dimension are 2.44 x 3.05 m. The wood has a k of 0.1505 W/m.K and is 25.4 mm thick. the glass is 3.18 mm thick and has a k of 0.692. the inside temperature is 299.9 K (26.7 degree Celsius) and the outside air temperature is 266.5 K . The convection coefficient hi on the inside wall of the glass and the wood is estimated as 8.5 W/m².K ; the outside ho is also estimated as 8.5 for both surfaces . Calculate the heat loss through the wooden wall, through the glass and the total

A fuel Oil temperature is decreased from 150°C to 90°C and water temperature is increased from 25°C to 70°C in a counter current double pipe heat exchanger. What is the value of LMTD?

For a liquid being cooled, the viscosity correction factor is (greater than less than/equal to) unity, and for a liquid being heated, the viscosity correction factor is ____(greater than/less than/equal to) unity? (Sieder-Tate equation) (write the answers in the same order of blanks given)